Abstracts South West Orthopaedic Club 2 nd May 1981 , Truro PRIDIE MEMORIAL LECTURE

South West Orthopaedic Club 2nd May 1981, Truro PRIDIE MEMORIAL LECTURE Mr. M. A. R. Freeman London Hospital Medical College The results were reported of double cup hip replacements carried out at The London Hospital between the 1st January 1975 and the 31st December 1977. The prosthesis used during this period consisted of a cemented metalic femoral component and a cemented, approximately hemispherical, polyethylene acetabular component. Successfully replaced hips during this period are now available with a follow-up of up to six years. Their symptomatic state is equivalent to that of conventional hip replacement. Thirty-five percent of hips treated in the period have failed although not all have subsequently required revision surgery. The principle causes of failure were as follows: 1. Errors of Indication Forty percent of all failures were in patients having a replacement for inflammatory arthritis (rheumatoid arthritis or ankylosing spondylitis) or rapidly progressive osteoarthrosis. It is now felt that the operation should be carried out rarely, if at all, in these conditions. 2. Femoral Failures These were seen as a consequence of two technical errors: notching of the superior neck (which it is speculated may interfere with the interosseous blood supply to the head and thus lead to femoral loosening) and varus placement of the femoral component (which may lead to subcapital fracture or femoral loosening). 3. Errors of Acetabular Design and Implantation Technique The fundamental problem in this connection is that the acetabular component used in the period under study was too large and thus tended to protrude from the pelvis. The protruding polyethylene sometimes impinged against the femoral neck, resulting in pain, stiffness and or acetabular loosening. Other factors which it was thought might increase the chances of acetabular loosening and perhaps increase the incidence of significance radiolucent lines around the acetabular cement were: the presence of excess cement in the floor of the acetabulum, the presence of too thin a layer of cement superiorly, the fact that the wall thickness of the polyethylene component is less than that of a conventional prosthesis and finally that the radius of the femoral head is greater than that of a conventional prosthesis. Some possible solutions to these problems, used clinically in the years 1980/81, were discussed.

The results were reported of double cup hip replacements carried out at The London Hospital Successfully replaced hips during this period are now available with a follow-up of up to six years. Their symptomatic state is equivalent to that of conventional hip replacement. Thirty-five percent of hips treated in the period have failed although not all have subsequently required revision surgery. The principle causes of failure were as follows:

Errors of Indication
Forty percent of all failures were in patients having a replacement for inflammatory arthritis (rheumatoid arthritis or ankylosing spondylitis) or rapidly progressive osteoarthrosis. It is now felt that the operation should be carried out rarely, if at all, in these conditions.

Femoral Failures
These were seen as a consequence of two technical errors: notching of the superior neck (which it is speculated may interfere with the interosseous blood supply to the head and thus lead to femoral loosening) and varus placement of the femoral component (which may lead to subcapital fracture or femoral loosening). 3. Errors of Acetabular Design and Implantation Technique The fundamental problem in this connection is that the acetabular component used in the period under study was too large and thus tended to protrude from the pelvis. The protruding polyethylene sometimes impinged against the femoral neck, resulting in pain, stiffness and or acetabular loosening. Other factors which it was thought might increase the chances of acetabular loosening and perhaps increase the incidence of significance radiolucent lines around the acetabular cement were: the presence of excess cement in the floor of the acetabulum, the presence of too thin a layer of cement superiorly, the fact that the wall thickness of the polyethylene component is less than that of a conventional prosthesis and finally that the radius of the femoral head is greater than that of a conventional prosthesis. Some possible solutions to these problems, used clinically in the years 1980/81, were discussed. osteoarthritis and the remainder suffered from rheumatoid arthritis. The first 23 patients were nursed post-operatively with the knee in extension for two weeks: four of these patients required manipulation under anaesthesia in the postoperative period. A post-operative knee flexion regime was introduced after Case 24 and no subsequent patient has required manipulation under anaesthesia. There has been a reduction in the incidence of wound healing problems since this regime was introduced. There have been no cases of persistent deep joint infection, although 2 patients developed late infection, one due to a streptococcal cellulitis which was successfully treated by antibiotics and the second due to a traumatic leg ulceration which led to septicaemia and death. Two patients developed a late low grade inflammatory response which has been controlled by antibiotics.
A clinical and radiological review has been carried out by CEA and PCM on the first 55 cases which have been followed for 10-60 months. Six patients have died (seven knees) and 3 patients are unavailable for follow up. Forty-five knees have been examined in 40 patients and the results of this review are presented. A subjective assessment of the patients' satisfaction has been carried out using a visual analogue scale: 71% were enthusiastic or very satisfied, 7% non-committal and 22% were disappointed. A more objective grading system was designed, based on Insall's scoring system but weighted towards pain and function. 66% of the knees had an excellent or good result. 22% were fair and 11% were poor. The most important late complication was that of loosening of the tibial component which was definitely present in 8 knees and possibly present in 4 knees. Four of these have been revised and 2 are now satisfactory. Four remaining patients have a loose prosthesis, however, two have satisfactory knees and a further two will be revised shortly. There are four further cases which have significant pain which could be due to impingement or patello-femoral changes. 72% of the cases have excellent relief from pain. Of those patients with moderate or severe pain, the cause is loosening in half and other causes are patello-femoral pain, hip pain or tibio-femoral impingement. Analysis of knee movements shows that only two patients have a maximum of less than 80? and four patients have a fixed flexion deformity of 20? or more. Twenty-nine femoral fractures occurring after operation in association with cemented hip endoprostheses were studied. The majority occurred at the tip of the prosthesis (Type III), though fractures around the stem (Type II) and distal to the prosthesis (Type IV) also occurred. Four fractures were through known cortical defects, and these all occurred within one year. However, the remaining 25 occurred on average 7.7 years after operation and the possibility of femoral shaft weakening due to the presence of a rigid prosthesis is raised.
Non-operative management led to loosening of the femoral component following Type II fractures, and mal-union or non-union is all Type III fractures. Operative results were marred by infection, bending and malposition of the prosthesis. However, in the light of modern knowledge, many of these problems are avoidable, and operative management of all except Type IV fractures is therefore advocated. (ii) Posterior type bears the attachment of the posterior cruciate ligament. Fresh fractures of the above types ought to be reduced anatomically and better to be internally fixed.
Failure to do so will result in non-union which would cause block to full extension in the anterior type and giving way in the posterior type. This Paper deals with the treatment of ununited fractures of the intercondylar area of the tibia and its problems. Four cases of the anterior type were dealt with. All presented with 30-40? block to full extension. Pre-operative symptoms and signs were the same in all patients except three with weakness of wrist extension, thus apart from these three who probably had a true radial tunnel syndrome it was felt that the same complaint was being treated by two different operations.
The results of operation were 89% success for the ECRB legthening and 80% success for radial nerve neurolysis, thus was not significantly different.
It was shown that broad and tender scar was a significant complication of posterior interosseous nerve decompression.
A cadaver dissection was illustrated to demonstrate that the operation of posterior interosseous nerve neurolysis could work by releasing tension on the common extensor origin by dividing the superficial leaf of supinator, this mechanism being the same as lengthening the extensor carpi brevis tendon and threrfore not necessarily due to decompressing the posterior interosseous nerve.
It was concluded that of the two operations the Garden procedure was the one of choice.

COMPARISON OF MENISCECTOMY BY
'OPEN' AND 'CLOSED' TECHNIQUES P. K. Peace, Truro The importance of partial rather than total meniscectomy was stressed and reference made to the pioneering work of Jackson in Toronto who first performed a partial meniscectomy by the 'closed' technique in 1970 and more recently by Dandy in Newmarket. A small series was submitted following results of questionnaires sent to 57 patients. 46 replies were received but 14 of these were excluded because of severe osteo-arthrosis or instability of the knee. 16 patients were reviewed in each group. The 'open' group having 14 males and 2 females with an average age of 38.3 years and the 'closed' group having 15 males and 1 female with an average of 34.7 years.
The operative details in the 'open' group were that all cases were subjected to preliminary arthroscopy, tourniquet then inflated after elevation of the leg and the knee was re-towelled and the surgeon regowned. A 3" oblique incision used and plaster immobilization for 10-14 days post-operatively.
The 'closed' technique was performed with a tournique inflated from the outset and 6mm incision on each side of the knee and a pressure bandage applied post-operatively.
In the 'open' group nearly all cases were involving the medial meniscus and in the 'closed' group there was a slight preponderance of lateral menisci involved. There were relatively few bucket handle tears in the 'closed' group mainly due to lack of experience during the period of review. This paper describes the evolution of the system of cast bracing for femoral shaft fractures currently sued in Exeter. Various modifications of the conventional cast brace have been introduced to overcome its disadvantages, and incorporated in the system during a prospective study over three years.
Thirty four patients were treated by early bracing at an average time of six weeks after fracture; thirty united without problems, although fractures of the upper shaft tended to unite in varus and flexion. Eight patients were treated by lat bracing at an average of 14 weeks after fracture and six united without problems. The commonest reason for discontinuation of bracing was skin maceration, especially when polythene components were used.
The system currently used is to reduce the fracture primarily by manipulation and maintain skeletal traction until the fracture is 'sticky'. A cast brace is then applied, on the hip table, over a tubigrip stocking. Well moulded gypsona is used for the thigh piece, connected to a plastic below knee cosmetic caliper with partly constrained metal coil twist-brace hinges. Radiological control is used to confirm a satisfactory position. Weight bearing and knee flexion are commenced in 24 hours, and the brace is maintained until union is evident radiologically. This system of treatment for femoral shaft fractures has been found to be effective and inexpensive, as well as having significant advantages over other methods.